It is probably against Facebook's TOS*, but slapping an affiliate banner on your profile page is fairly easy - get an account with a service such as LinkShare, register with a merchant program, grab an ad unit (a linked image), get MyHTML application (I think SuperWall would work, too, but I haven't tried), copy-paste the code, and you are in business. Similarly, you can embed a simple pixel-based traffic counter from a service like StatCounter.

Or you could drive traffic to your blog by installing the Blog RSS Feed Reader application that posts daily summaries of your headlines to your mini-feed for all the friends to see.

Are we going to see more profile spam that is so ubiquitous on MySpace and in the darker quarters of YouTube? Don't know; the lack of anonymity on Facebook is kind of a game killer.

On a related note:

NY Times: "More than 1,500 Facebook users have started placing advertisements on their own profile pages — despite the social networking site’s rule against such ads. They are posting them with the help of a Montreal-based company called Weblo, an advertising network that sells ads onto people’s blogs and social networking profile pages."

In July, Mashable put together a list of 5 ways to make money with Facebook that included Amazon affiliate links and selling services with micropayments.

*From Facebook's TOS: "In addition, you agree not to use the Service or the Site to [...] upload, post, transmit, share or otherwise make available any unsolicited or unauthorized advertising, solicitations, promotional materials, "junk mail," "spam," "chain letters," "pyramid schemes," or any other form of solicitation."